For ski resorts, special vehicles are used in preparing the foundation for the ski runs and the cross-country trails. These special vehicles, so called snowgrooming vehicles, are track-driven in order to be able to manoeuvre. They are equipped with snow forming devices that are pulled behind for smoothing the surface. Further they are arranged with hydraulically manoeuvred ploughs in the front for transporting snow, such as to cut off bumps and fill deeper tracks and cavities.
During recent years the demands on a more varied skiing in the ski runs has increased, in particular with the arrival of snowboard and its utilisers, but also for ordinary skiing. For that the ski run areas have been designed with different “artificial” configurations, such as mogules, jumps and so called half-pipes. The latter is mainly U-shaped runs where the riders go up and down on the sides and perform different tricks and stunts. These designs demand relatively large amount of work to build up and maintain, for which the conventional snowgrooming vehicles are not optimally designed.
In order to overcome the drawbacks associated with the conventional machines and devices used for creating specially shaped ski-areas, patent application PCT/SE01/00206, discloses a working device comprising an arm rotatably arranged to a stand and that the arm is jointed. The arm is further also slidable in the longitudinal direction for altering the length of the arm. At the end of the arm, a number of different work tools can be attached, such as for example a thrower for removing and forming larger amounts of snow, a preparation device for fine preparation, shovel, work platform, bush cutter, gripping means, and other tools. The stand is designed as an individual self-supported unit that can be releasably attached to a vehicle.
This makes it very simple to attach and detach the device according to need, which provides a very flexible way of working and which for example provides for a snowgrooming vehicle, which is used in ski run areas for preparing the ski runs, to readily attach the device in order to perform machining and preparations of half-pipes and the like. Due to the design of the arm with its joint and the moving in and out of the outreach, advantages are obtained in that a very good control of the working unit can be achieved regarding the desired forms, radii and the like and in that the working area can be varied from very small protrusions to the really large half-pipes with wall heights of up to 6 meters.
The device according to PCT/SE01/00206 utilizes according to one embodiment a snow thrower specially adapted for the working and forming of snow surfaces such as half-pipes. This comprises a rotor with teeth designed and arranged such that a very good working is obtained also on very hard packed snow and where the worked snow can be controlled partly for obtaining an even worked surface, partly for removing and placing of the snow to selected places and partly.
However, the described snow-thrower, that is capable of moving large amounts of snow, is not ideal for finishing work, ie to prepare the shaped surfaces of a ski-area after a days use. These kinds of surfaces, such as half-pipes, often have track-marks, grooves and the like, that have to be removed or smoothed out, which means that it is only the very top layer that has to be worked, and quite often rather small amounts of snow that has to be moved.